Air duct filter apparatus



FIG. 1 is a front plan view of the air duct filter apparatus of thepresent invention;

FIG. 2 is a back plan view of the air duct filter apparatus of FIG. 1;

FIG. 3 is a left side plan view of the air duct filter apparatus of FIG.1;

FIG. 4 is a right side plan view of the air duct filter apparatus ofFIG. 1;

FIG. 5 is a top plan view of the air duct filter apparatus of FIG. 1;and,

FIG. 6 is a bottom plan view of the air duct filter apparatus of FIG. 1.

The ornamental design for an air duct filter apparatus, as shown.